It is well known in the art that biological tissues can be sliced into thin sections on a microtome for subsequent microscopic examination by a pathologist, for example. In order to prepare the specimen for such slicing it must first be processed with several fluids to dehydrate the tissue, to clear the tissue with a suitable oil and then to infiltrate the tissue with a paraffin wax or a combination of wax and resinous material. This processing has been conveniently carried out by placing the specimen in a fluid-permeable capsule and successively submerging the capsule in the necessary fluids. The resulting processed specimen is then removed from the capsule and embedded in a block of paraffin wax for subsequent mounting in a microtome for slicing.
U.S. Pat. No. 4,220,252 describes a unitary biological specimen processing apparatus comprising an open-topped, perforated receptacle member, a cooperable perforated cover member attached to said receptable member by a frangible hinge portion, said receptacle and cover members being capable of relative movement about said hinge portion from a first position permitting placement of a specimen in said receptacle member to a second position wherein the open top of said receptacle member is closed by said cover member, and cooperable detent and abutment means on said receptacle and cover members interengageable when said receptacle and cover members are in said second position to hold said members in said second position independently of said frangible hinge portion.
Thereby is obtained an apparatus which initially has a cover member attached by a hinge portion to a base member but which can remain mated against the base member in a closed position even with the hinge portion broken.
This prior apparatus had the disadvantage that if the hinge portion was very frangible and was broken before the cover member was mated against the base member, the user of the apparatus could loose or drop the specimen because of the lost hinge function. Contamination of the specimens and loss of expensive time could thus result. If, however, the frangible hinge portion was strong enough to resist the 180 degree of the cover member turning about into the mating position with the receptacle member, there would be a risk that it would be difficult to remove the cover member from the receptacle member when processing of the specimen was finished.
There is thus a commercial need for a unitary biological processing apparatus which has a hinge portion which is so frangible that it is broken just before the cover member is mated against the receptacle member, but without the risk that the hinge function is eliminated when the hinge portion is broken.